Treated planographic printing plate



.as those which .for this purpose and ing crayons, andlthe Patented Sept. 7, 1948 UNITED, STATES PATENT orrlca Charles H. signer to tion, Wilmington, DeL, ware No Drawing.

This invention relates to lug. More particularly, this paper planographic printing plates and to a process and solution for eliminating so-called finger prints and so-called resin specks planographic print- As is well known in the art of planographic printing paper planographic printing plates, such are frequently encountered in the copies made from paper planographic printing plates. These rosin specks are also receptive to the greasy or fatty acid-containing inks used in planographic specks in the copies made from paperplanm graphic printing plates. However, insofar as I am aware of all of such been unsuccessful in eliminating the reproducinvention relates to specks in the copies Van Dusen, Jr., Willoughby, Ohio, as-

Addressograph-Multigraph Corporaa corporation of Dela- Applicatlonlanuary 24, 1947, Serial No. 724,231

4 Claims. (Cl. lob-149.2)

age thereon, not only eflectively eliminates or prevents the reproduction of any finger prints or resin or rosin particles or so-called resin or rosin made from the thus treated paper planographic printing plate but which likewise does not in any way weaken or otherwise interfere with the image-receptive or image-reproducing characteristics ot. the various planographic image-forming materials which may be employed in forming images on the treated paper planozraphic printing plates including type- ,wr'iter image-forming materials, planographic materials have either weakening the image-reproducing characteristics of the image form pianographic printing plate by means of the various planographic image-forming materials used which include typewriter image-forming inks,

like.

In and as the present invention I have, however, found a material which when applied as a water solution thereof to a dry or to a wet paper planographic printing plate, and the plate then dried, preparatory to placing a lithographic imed on the master paper solution thereto. The t inks, crayons, and

image-forming inks, and Accordingly, an object the like. of the present invention is to provide a novel process and .solution for eliminating and preventing the reproduction of finger prints and so-called resin and rosin specks in the copies made from paper pianographic printing plates.

Another object of the present invention is to provide a novel process and solution for elimiages on such paper planographic printing plates including planographic image-forming typewriter ribbons, inks, crayons, and the like.

An additional object of the present invention image-reproducing characterismaterials forming images on paper planographic printing plates including planographic image-forming typewriter ribbons,

the like.

In the practice of brushing, spraying or otherwise applying the section of the plate,

preferably run between a pair of squeeze rolls and allowed to dry whereupon it may be provided with a lithographic image by means of any suitable lithographic image-forming material, such as any of those hereinbefore referred to, and then treated with an aqueous planographic etching or dampening solution to condition the plate for use in a planographic printing operation. The resulting plate is thus a paper planographic printing plate impregnated with 2 amino, 2 methyl, 1,3 propanediol. I

It has been found that parchment or like paper planographic printing plates treated with the new solution not only do not reproduce finger prints or resin or rosin specks in the copies made therefrom but have good image-receptive and good image-reproducing characteristics and that the new solution does not in any way weaken or otherwise interfere with the image-reproducing characteristics of the planographic image-forming material employed in forming the image thereon.

The effectiveness of the new process and solution were demonstrated by applying the new solution to approximately one-half of the surface area of the printing surface of a parchment planographic printing plate which was known to reproduce rosin specks due to the naturally occurring wood rosin therein. The other half of the printing surface of the said parchment plate was allowed to remain untreated. The thus treated parchment plate was then thoroughly dehydrated at room temperature and then finger printed throughout its entire printing surface including both the treated and the untreated areas thereof. One section of the thus treated parchment plate was thereupon exposed to natural diffused sunlight for a period of about four minutes and theother section was exposed to the rays of an ultra-violet lamp for a period of fifteen minutes. (Both of these treatments are known to exaggerate the image-reproducing characteristics of finger prints upon and of wood rosin specks in parchment or like paper planographic printing lates.) After having been thus exposed a lithographic image was applied to each by means of a suitable'lithographic image-forming material, whereupon both sections of the thus treated and exposed parchment plate were treated with an aqueous planographing etching and repellent solution, fastened in position of use upon the plate cylinder of a rotary offset planographic duplicating press, and a satisfactory edition ofcopies run therefrom. However, the copies reproduced .from those portions of the parchment planographic printing plate which 'was treated with the' new solution did not exhibit either finger printsor so-called rosin specks whereas both finger prints and rosin specks appeared prominently in the copies re-, produced from the untreated portions of the plate. Moreover, that area or section of the new plate which had been treated with the new solution exhibited equally as good image-reproducing characteristics and equally as long editions were reproduced therefrom as were exhibited by and reproduced from the other area or section of the plate which had not been so treated.

It has been found that the above named percentage, namely, five per cent, by weight, of 2 amino, 2 methyl, 1,3 propanediol in water is the optimum percentage when the new solution is applied to a dry paper planographic printing plate or mat. I have the new solution is applied to a wet paper planographic printing plate or mat the concentration of the solution and the quantity thereof applied is then preferably adjusted so that the resulting solution, thus diluted with and by the water in the wet paper planographic printing plate to which it is applied, is equivalent to a five (5) per cent solution, by weight, and when so controlled produces highly satisfactory solutions on paper planographic printing plates impregnated therewith. However, the exact amount of the material to be incorporated in a parchment or like paper planographic printing plate depends upon and may be adjusted to variable conditions including the condition of the sheet at the time the material is applied thereto, that is, whether wet or dry, its moisture content if nominally a socalled dry sheet, revailing atmospheric or room humidity conditions, and the like.

It will thus be seen from the foregoing description that the present invention provides a novel process and solution for eliminating both finger prints and rosinv specks in the copies reproduced from paper planographic printing plates treated with the new solution, and without interfering with either the image-receptive or the image-reproducing characteristics of paper planographic printing plates treated with the new solution, and thus provides a paper planographic printing plate having the desirable advantages and characteristics, and which accomplishes its intended objects, including those hereinbefore pointed out and others which are inherent in the invention.

I claim:

1. A paper planographic printing plate impregnated with 2 amino, 2 methyl, 1,3 propanediol.. 4

2. A parchment planographic printing plate impregnated with 2 amino, 2 methyl, 1,3 propanediol;

3. A paper planographic printing plate impregnated with the dried residue of a five per cent water solution of 2 amino, 2 methyl, 1,3 propanediol.

4. A parchment planographic printing plate impregnated with the dried residue of a five per cent water solution of 2 amino, 2 methyl, 1,3 propanediol.

CHARLES H. VAN DUSEN, JR.

REFERENCES ,CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name v Date Bassist Apr. 10,-1945 OTHER REFERENCES Chemical Industries, vol. XLV, p. 666, The Nitroparaflins and their Derivations, December '7, 1939.

likewise found that when 

